I. Our preliminary data suggests that differences in gene expression in the canonical circadian clock genes do not explain the long circadian period we observed in both male and female flies. We are therefore in the process of identifying potential candidate genes using RNA-Seq. Transcriptome profiles will be established for males and females of the long period line, and compared to flies having a normal circadian period. We are measuring gene expression across twelve time points in order to identify differences in cycling across a normal 24-hour day. We have frozen three replicates of 150 heads for each time point, sex, and genotype under dark:dark conditions.